Merge lp:~1chb1n/charm-helpers/amulet-ceph-cinder-updates into lp:charm-helpers

[Ryan Beisner]

# updates for ceph/cinder amulet tests:
Update validate_config_data - enable use of boolean comparison methods

Add check_commands_on_units - check lists of commands on lists of units

Add authenticate_cinder_admin

Add create_cinder_volume

Update create_cirros_image to use generic resource status methods, add
validation.

Simplify delete_image to use generic resource_delete method.

Simplify delete_instance to use generic resource_delete method.

These changes preserve existing behavior while adding new capabilities.

# related / dependent charm MPs:
https://code.launchpad.net/~1chb1n/charms/trusty/ceph/next-amulet-update/+merge/262016

https://code.launchpad.net/~1chb1n/charms/trusty/ceph-osd/next-amulet-update/+merge/262249

https://code.launchpad.net/~1chb1n/charms/trusty/ceph-radosgw/next-amulet-update/+merge/262599

https://code.launchpad.net/~1chb1n/charms/trusty/cinder/next-amulet-updates/+merge/262772

https://code.launchpad.net/~1chb1n/charms/trusty/cinder-ceph/next-amulet-updates/+merge/262910

https://code.launchpad.net/~1chb1n/charms/trusty/ceilometer-agent/next-amulet-add-initial/+merge/263040

https://code.launchpad.net/~1chb1n/charms/trusty/ceilometer/next-amulet-add-subordinate-checks/+merge/263147

https://code.launchpad.net/~1chb1n/charms/trusty/keystone/next-amulet-update/+merge/263460

https://code.launchpad.net/~1chb1n/charms/trusty/mysql/trunk-amulet-update-vivid/+merge/263428

https://code.launchpad.net/~1chb1n/charms/trusty/neutron-api/next-amulet-update/+merge/263594

https://code.launchpad.net/~1chb1n/charms/trusty/glance/next-amulet-update/+merge/263413

https://code.launchpad.net/~1chb1n/charms/trusty/neutron-gateway/next-amulet-update/+merge/263658

[Corey Bryant (corey.bryant)]

Reviewed with comments below.

review: Needs Fixing

[Ryan Beisner (1chb1n)]

Good input, appreciate it! See comments inline.

[Ryan Beisner (1chb1n)]

Updated comments inline.

[Corey Bryant (corey.bryant)]

review: Approve

=== modified file 'charmhelpers/contrib/amulet/utils.py'
--- charmhelpers/contrib/amulet/utils.py	2015-06-12 14:38:38 +0000
+++ charmhelpers/contrib/amulet/utils.py	2015-06-29 13:19:53 +0000
@@ -14,6 +14,7 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with charm-helpers.  If not, see <http://www.gnu.org/licenses/>.
 
+import amulet
 import ConfigParser
 import distro_info
 import io
@@ -173,6 +174,11 @@
 
            Verify that the specified section of the config file contains
            the expected option key:value pairs.
+
+           Compare expected dictionary data vs actual dictionary data.
+           The values in the 'expected' dictionary can be strings, bools, ints,
+           longs, or can be a function that evaluates a variable and returns a
+           bool.
            """
         self.log.debug('Validating config file data ({} in {} on {})'
                        '...'.format(section, config_file,
@@ -185,9 +191,20 @@
         for k in expected.keys():
             if not config.has_option(section, k):
                 return "section [{}] is missing option {}".format(section, k)
-            if config.get(section, k) != expected[k]:
+
+            actual = config.get(section, k)
+            v = expected[k]
+            if (isinstance(v, six.string_types) or
+                    isinstance(v, bool) or
+                    isinstance(v, six.integer_types)):
+                # handle explicit values
+                if actual != v:
+                    return "section [{}] {}:{} != expected {}:{}".format(
+                           section, k, actual, k, expected[k])
+            # handle function pointers, such as not_null or valid_ip
+            elif not v(actual):
                 return "section [{}] {}:{} != expected {}:{}".format(
-                       section, k, config.get(section, k), k, expected[k])
+                       section, k, actual, k, expected[k])
         return None
 
     def _validate_dict_data(self, expected, actual):
@@ -195,7 +212,7 @@
 
            Compare expected dictionary data vs actual dictionary data.
            The values in the 'expected' dictionary can be strings, bools, ints,
-           longs, or can be a function that evaluate a variable and returns a
+           longs, or can be a function that evaluates a variable and returns a
            bool.
            """
         self.log.debug('actual: {}'.format(repr(actual)))
@@ -206,8 +223,10 @@
                 if (isinstance(v, six.string_types) or
                         isinstance(v, bool) or
                         isinstance(v, six.integer_types)):
+                    # handle explicit values
                     if v != actual[k]:
                         return "{}:{}".format(k, actual[k])
+                # handle function pointers, such as not_null or valid_ip
                 elif not v(actual[k]):
                     return "{}:{}".format(k, actual[k])
             else:
@@ -406,3 +425,109 @@
         """Convert a relative file path to a file URL."""
         _abs_path = os.path.abspath(file_rel_path)
         return urlparse.urlparse(_abs_path, scheme='file').geturl()
+
+    def check_commands_on_units(self, commands, sentry_units):
+        """Check that all commands in a list exit zero on all
+        sentry units in a list.
+
+        :param commands:  list of bash commands
+        :param sentry_units:  list of sentry unit pointers
+        :returns: None if successful; Failure message otherwise
+        """
+        self.log.debug('Checking exit codes for {} commands on {} '
+                       'sentry units...'.format(len(commands),
+                                                len(sentry_units)))
+        for sentry_unit in sentry_units:
+            for cmd in commands:
+                output, code = sentry_unit.run(cmd)
+                if code == 0:
+                    self.log.debug('{} `{}` returned {} '
+                                   '(OK)'.format(sentry_unit.info['unit_name'],
+                                                 cmd, code))
+                else:
+                    return ('{} `{}` returned {} '
+                            '{}'.format(sentry_unit.info['unit_name'],
+                                        cmd, code, output))
+        return None
+
+    def get_process_id_list(self, sentry_unit, process_name):
+        """Get a list of process ID(s) from a single sentry juju unit
+        for a single process name.
+
+        :param sentry_unit: Pointer to amulet sentry instance (juju unit)
+        :param process_name: Process name
+        :returns: List of process IDs
+        """
+        cmd = 'pidof {}'.format(process_name)
+        output, code = sentry_unit.run(cmd)
+        if code != 0:
+            msg = ('{} `{}` returned {} '
+                   '{}'.format(sentry_unit.info['unit_name'],
+                               cmd, code, output))
+            amulet.raise_status(amulet.FAIL, msg=msg)
+        return str(output).split()
+
+    def get_unit_process_ids(self, unit_processes):
+        """Construct a dict containing unit sentries, process names, and
+        process IDs."""
+        pid_dict = {}
+        for sentry_unit, process_list in unit_processes.iteritems():
+            pid_dict[sentry_unit] = {}
+            for process in process_list:
+                pids = self.get_process_id_list(sentry_unit, process)
+                pid_dict[sentry_unit].update({process: pids})
+        return pid_dict
+
+    def validate_unit_process_ids(self, expected, actual):
+        """Validate process id quantities for services on units."""
+        self.log.debug('Checking units for running processes...')
+        self.log.debug('Expected PIDs: {}'.format(expected))
+        self.log.debug('Actual PIDs: {}'.format(actual))
+
+        if len(actual) != len(expected):
+            return ('Unit count mismatch.  expected, actual: {}, '
+                    '{} '.format(len(expected), len(actual)))
+
+        for (e_sentry, e_proc_names) in expected.iteritems():
+            e_sentry_name = e_sentry.info['unit_name']
+            if e_sentry in actual.keys():
+                a_proc_names = actual[e_sentry]
+            else:
+                return ('Expected sentry ({}) not found in actual dict data.'
+                        '{}'.format(e_sentry_name, e_sentry))
+
+            if len(e_proc_names.keys()) != len(a_proc_names.keys()):
+                return ('Process name count mismatch.  expected, actual: {}, '
+                        '{}'.format(len(expected), len(actual)))
+
+            for (e_proc_name, e_pids_length), (a_proc_name, a_pids) in \
+                    zip(e_proc_names.items(), a_proc_names.items()):
+                if e_proc_name != a_proc_name:
+                    return ('Process name mismatch.  expected, actual: {}, '
+                            '{}'.format(e_proc_name, a_proc_name))
+
+                a_pids_length = len(a_pids)
+                if e_pids_length != a_pids_length:
+                    return ('PID count mismatch. {} ({}) expected, actual: '
+                            '{}, {} ({})'.format(e_sentry_name, e_proc_name,
+                                                 e_pids_length, a_pids_length,
+                                                 a_pids))
+                else:
+                    self.log.debug('PID check OK: {} {} {}: '
+                                   '{}'.format(e_sentry_name, e_proc_name,
+                                               e_pids_length, a_pids))
+        return None
+
+    def validate_list_of_identical_dicts(self, list_of_dicts):
+        """Check that all dicts within a list are identical."""
+        hashes = []
+        for _dict in list_of_dicts:
+            hashes.append(hash(frozenset(_dict.items())))
+
+        self.log.debug('Hashes: {}'.format(hashes))
+        if len(set(hashes)) == 1:
+            self.log.debug('Dicts within list are identical')
+        else:
+            return 'Dicts within list are not identical'
+
+        return None

=== modified file 'charmhelpers/contrib/openstack/amulet/deployment.py'
--- charmhelpers/contrib/openstack/amulet/deployment.py	2015-06-11 19:46:51 +0000
+++ charmhelpers/contrib/openstack/amulet/deployment.py	2015-06-29 13:19:53 +0000
@@ -79,9 +79,9 @@
         services.append(this_service)
         use_source = ['mysql', 'mongodb', 'rabbitmq-server', 'ceph',
                       'ceph-osd', 'ceph-radosgw']
-        # Openstack subordinate charms do not expose an origin option as that
-        # is controlled by the principle
-        ignore = ['neutron-openvswitch']
+        # Most OpenStack subordinate charms do not expose an origin option
+        # as that is controlled by the principle.
+        ignore = ['cinder-ceph', 'hacluster', 'neutron-openvswitch']
 
         if self.openstack:
             for svc in services:
@@ -148,3 +148,36 @@
             return os_origin.split('%s-' % self.series)[1].split('/')[0]
         else:
             return releases[self.series]
+
+    def get_ceph_expected_pools(self, radosgw=False):
+        """Return a list of expected ceph pools in a ceph + cinder + glance
+        test scenario, based on OpenStack release and whether ceph radosgw
+        is flagged as present or not."""
+
+        if self._get_openstack_release() >= self.trusty_kilo:
+            # Kilo or later
+            pools = [
+                'rbd',
+                'cinder',
+                'glance'
+            ]
+        else:
+            # Juno or earlier
+            pools = [
+                'data',
+                'metadata',
+                'rbd',
+                'cinder',
+                'glance'
+            ]
+
+        if radosgw:
+            pools.extend([
+                '.rgw.root',
+                '.rgw.control',
+                '.rgw',
+                '.rgw.gc',
+                '.users.uid'
+            ])
+
+        return pools

=== modified file 'charmhelpers/contrib/openstack/amulet/utils.py'
--- charmhelpers/contrib/openstack/amulet/utils.py	2015-06-11 14:30:25 +0000
+++ charmhelpers/contrib/openstack/amulet/utils.py	2015-06-29 13:19:53 +0000
@@ -14,16 +14,20 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with charm-helpers.  If not, see <http://www.gnu.org/licenses/>.
 
+import amulet
+import json
 import logging
 import os
 import six
 import time
 import urllib
 
+import cinderclient.v1.client as cinder_client
 import glanceclient.v1.client as glance_client
 import heatclient.v1.client as heat_client
 import keystoneclient.v2_0 as keystone_client
 import novaclient.v1_1.client as nova_client
+import swiftclient
 
 from charmhelpers.contrib.amulet.utils import (
     AmuletUtils
@@ -171,6 +175,16 @@
         self.log.debug('Checking if tenant exists ({})...'.format(tenant))
         return tenant in [t.name for t in keystone.tenants.list()]
 
+    def authenticate_cinder_admin(self, keystone_sentry, username,
+                                  password, tenant):
+        """Authenticates admin user with cinder."""
+        # NOTE(beisner): cinder python client doesn't accept tokens.
+        service_ip = \
+            keystone_sentry.relation('shared-db',
+                                     'mysql:shared-db')['private-address']
+        ept = "http://{}:5000/v2.0".format(service_ip.strip().decode('utf-8'))
+        return cinder_client.Client(username, password, tenant, ept)
+
     def authenticate_keystone_admin(self, keystone_sentry, user, password,
                                     tenant):
         """Authenticates admin user with the keystone admin endpoint."""
@@ -212,9 +226,29 @@
         return nova_client.Client(username=user, api_key=password,
                                   project_id=tenant, auth_url=ep)
 
+    def authenticate_swift_user(self, keystone, user, password, tenant):
+        """Authenticates a regular user with swift api."""
+        self.log.debug('Authenticating swift user ({})...'.format(user))
+        ep = keystone.service_catalog.url_for(service_type='identity',
+                                              endpoint_type='publicURL')
+        return swiftclient.Connection(authurl=ep,
+                                      user=user,
+                                      key=password,
+                                      tenant_name=tenant,
+                                      auth_version='2.0')
+
     def create_cirros_image(self, glance, image_name):
-        """Download the latest cirros image and upload it to glance."""
-        self.log.debug('Creating glance image ({})...'.format(image_name))
+        """Download the latest cirros image and upload it to glance,
+        validate and return a resource pointer.
+
+        :param glance: pointer to authenticated glance connection
+        :param image_name: display name for new image
+        :returns: glance image pointer
+        """
+        self.log.debug('Creating glance cirros image '
+                       '({})...'.format(image_name))
+
+        # Download cirros image
         http_proxy = os.getenv('AMULET_HTTP_PROXY')
         self.log.debug('AMULET_HTTP_PROXY: {}'.format(http_proxy))
         if http_proxy:
@@ -223,33 +257,51 @@
         else:
             opener = urllib.FancyURLopener()
 
-        f = opener.open("http://download.cirros-cloud.net/version/released")
+        f = opener.open('http://download.cirros-cloud.net/version/released')
         version = f.read().strip()
-        cirros_img = "cirros-{}-x86_64-disk.img".format(version)
+        cirros_img = 'cirros-{}-x86_64-disk.img'.format(version)
         local_path = os.path.join('tests', cirros_img)
 
         if not os.path.exists(local_path):
-            cirros_url = "http://{}/{}/{}".format("download.cirros-cloud.net",
+            cirros_url = 'http://{}/{}/{}'.format('download.cirros-cloud.net',
                                                   version, cirros_img)
             opener.retrieve(cirros_url, local_path)
         f.close()
 
+        # Create glance image
         with open(local_path) as f:
             image = glance.images.create(name=image_name, is_public=True,
                                          disk_format='qcow2',
                                          container_format='bare', data=f)
-        count = 1
-        status = image.status
-        while status != 'active' and count < 10:
-            time.sleep(3)
-            image = glance.images.get(image.id)
-            status = image.status
-            self.log.debug('image status: {}'.format(status))
-            count += 1
-
-        if status != 'active':
-            self.log.error('image creation timed out')
-            return None
+
+        # Wait for image to reach active status
+        img_id = image.id
+        ret = self.resource_reaches_status(glance.images, img_id,
+                                           expected_stat='active',
+                                           msg='Image status wait')
+        if not ret:
+            msg = 'Glance image failed to reach expected state.'
+            amulet.raise_status(amulet.FAIL, msg=msg)
+
+        # Re-validate new image
+        self.log.debug('Validating image attributes...')
+        val_img_name = glance.images.get(img_id).name
+        val_img_stat = glance.images.get(img_id).status
+        val_img_pub = glance.images.get(img_id).is_public
+        val_img_cfmt = glance.images.get(img_id).container_format
+        val_img_dfmt = glance.images.get(img_id).disk_format
+        msg_attr = ('Image attributes - name:{} public:{} id:{} stat:{} '
+                    'container fmt:{} disk fmt:{}'.format(
+                        val_img_name, val_img_pub, img_id,
+                        val_img_stat, val_img_cfmt, val_img_dfmt))
+
+        if val_img_name == image_name and val_img_stat == 'active' \
+                and val_img_pub is True and val_img_cfmt == 'bare' \
+                and val_img_dfmt == 'qcow2':
+            self.log.debug(msg_attr)
+        else:
+            msg = ('Volume validation failed, {}'.format(msg_attr))
+            amulet.raise_status(amulet.FAIL, msg=msg)
 
         return image
 
@@ -260,22 +312,7 @@
         self.log.warn('/!\\ DEPRECATION WARNING:  use '
                       'delete_resource instead of delete_image.')
         self.log.debug('Deleting glance image ({})...'.format(image))
-        num_before = len(list(glance.images.list()))
-        glance.images.delete(image)
-
-        count = 1
-        num_after = len(list(glance.images.list()))
-        while num_after != (num_before - 1) and count < 10:
-            time.sleep(3)
-            num_after = len(list(glance.images.list()))
-            self.log.debug('number of images: {}'.format(num_after))
-            count += 1
-
-        if num_after != (num_before - 1):
-            self.log.error('image deletion timed out')
-            return False
-
-        return True
+        return self.delete_resource(glance.images, image, msg='glance image')
 
     def create_instance(self, nova, image_name, instance_name, flavor):
         """Create the specified instance."""
@@ -308,22 +345,8 @@
         self.log.warn('/!\\ DEPRECATION WARNING:  use '
                       'delete_resource instead of delete_instance.')
         self.log.debug('Deleting instance ({})...'.format(instance))
-        num_before = len(list(nova.servers.list()))
-        nova.servers.delete(instance)
-
-        count = 1
-        num_after = len(list(nova.servers.list()))
-        while num_after != (num_before - 1) and count < 10:
-            time.sleep(3)
-            num_after = len(list(nova.servers.list()))
-            self.log.debug('number of instances: {}'.format(num_after))
-            count += 1
-
-        if num_after != (num_before - 1):
-            self.log.error('instance deletion timed out')
-            return False
-
-        return True
+        return self.delete_resource(nova.servers, instance,
+                                    msg='nova instance')
 
     def create_or_get_keypair(self, nova, keypair_name="testkey"):
         """Create a new keypair, or return pointer if it already exists."""
@@ -339,6 +362,88 @@
         _keypair = nova.keypairs.create(name=keypair_name)
         return _keypair
 
+    def create_cinder_volume(self, cinder, vol_name="demo-vol", vol_size=1,
+                             img_id=None, src_vol_id=None, snap_id=None):
+        """Create cinder volume, optionally from a glance image, OR
+        optionally as a clone of an existing volume, OR optionally
+        from a snapshot.  Wait for the new volume status to reach
+        the expected status, validate and return a resource pointer.
+
+        :param vol_name: cinder volume display name
+        :param vol_size: size in gigabytes
+        :param img_id: optional glance image id
+        :param src_vol_id: optional source volume id to clone
+        :param snap_id: optional snapshot id to use
+        :returns: cinder volume pointer
+        """
+        # Handle parameter input and avoid impossible combinations
+        if img_id and not src_vol_id and not snap_id:
+            # Create volume from image
+            self.log.debug('Creating cinder volume from glance image...')
+            bootable = 'true'
+        elif src_vol_id and not img_id and not snap_id:
+            # Clone an existing volume
+            self.log.debug('Cloning cinder volume...')
+            bootable = cinder.volumes.get(src_vol_id).bootable
+        elif snap_id and not src_vol_id and not img_id:
+            # Create volume from snapshot
+            self.log.debug('Creating cinder volume from snapshot...')
+            snap = cinder.volume_snapshots.find(id=snap_id)
+            vol_size = snap.size
+            snap_vol_id = cinder.volume_snapshots.get(snap_id).volume_id
+            bootable = cinder.volumes.get(snap_vol_id).bootable
+        elif not img_id and not src_vol_id and not snap_id:
+            # Create volume
+            self.log.debug('Creating cinder volume...')
+            bootable = 'false'
+        else:
+            # Impossible combination of parameters
+            msg = ('Invalid method use - name:{} size:{} img_id:{} '
+                   'src_vol_id:{} snap_id:{}'.format(vol_name, vol_size,
+                                                     img_id, src_vol_id,
+                                                     snap_id))
+            amulet.raise_status(amulet.FAIL, msg=msg)
+
+        # Create new volume
+        try:
+            vol_new = cinder.volumes.create(display_name=vol_name,
+                                            imageRef=img_id,
+                                            size=vol_size,
+                                            source_volid=src_vol_id,
+                                            snapshot_id=snap_id)
+            vol_id = vol_new.id
+        except Exception as e:
+            msg = 'Failed to create volume: {}'.format(e)
+            amulet.raise_status(amulet.FAIL, msg=msg)
+
+        # Wait for volume to reach available status
+        ret = self.resource_reaches_status(cinder.volumes, vol_id,
+                                           expected_stat="available",
+                                           msg="Volume status wait")
+        if not ret:
+            msg = 'Cinder volume failed to reach expected state.'
+            amulet.raise_status(amulet.FAIL, msg=msg)
+
+        # Re-validate new volume
+        self.log.debug('Validating volume attributes...')
+        val_vol_name = cinder.volumes.get(vol_id).display_name
+        val_vol_boot = cinder.volumes.get(vol_id).bootable
+        val_vol_stat = cinder.volumes.get(vol_id).status
+        val_vol_size = cinder.volumes.get(vol_id).size
+        msg_attr = ('Volume attributes - name:{} id:{} stat:{} boot:'
+                    '{} size:{}'.format(val_vol_name, vol_id,
+                                        val_vol_stat, val_vol_boot,
+                                        val_vol_size))
+
+        if val_vol_boot == bootable and val_vol_stat == 'available' \
+                and val_vol_name == vol_name and val_vol_size == vol_size:
+            self.log.debug(msg_attr)
+        else:
+            msg = ('Volume validation failed, {}'.format(msg_attr))
+            amulet.raise_status(amulet.FAIL, msg=msg)
+
+        return vol_new
+
     def delete_resource(self, resource, resource_id,
                         msg="resource", max_wait=120):
         """Delete one openstack resource, such as one instance, keypair,
@@ -350,6 +455,8 @@
         :param max_wait: maximum wait time in seconds
         :returns: True if successful, otherwise False
         """
+        self.log.debug('Deleting OpenStack resource '
+                       '{} ({})'.format(resource_id, msg))
         num_before = len(list(resource.list()))
         resource.delete(resource_id)
 
@@ -411,3 +518,87 @@
             self.log.debug('{} never reached expected status: '
                            '{}'.format(resource_id, expected_stat))
             return False
+
+    def get_ceph_osd_id_cmd(self, index):
+        """Produce a shell command that will return a ceph-osd id."""
+        return ("`initctl list | grep 'ceph-osd ' | "
+                "awk 'NR=={} {{ print $2 }}' | "
+                "grep -o '[0-9]*'`".format(index + 1))
+
+    def get_ceph_pools(self, sentry_unit):
+        """Return a dict of ceph pools from a single ceph unit, with
+        pool name as keys, pool id as vals."""
+        pools = {}
+        cmd = 'sudo ceph osd lspools'
+        output, code = sentry_unit.run(cmd)
+        if code != 0:
+            msg = ('{} `{}` returned {} '
+                   '{}'.format(sentry_unit.info['unit_name'],
+                               cmd, code, output))
+            amulet.raise_status(amulet.FAIL, msg=msg)
+
+        # Example output: 0 data,1 metadata,2 rbd,3 cinder,4 glance,
+        for pool in str(output).split(','):
+            pool_id_name = pool.split(' ')
+            if len(pool_id_name) == 2:
+                pool_id = pool_id_name[0]
+                pool_name = pool_id_name[1]
+                pools[pool_name] = int(pool_id)
+
+        self.log.debug('Pools on {}: {}'.format(sentry_unit.info['unit_name'],
+                                                pools))
+        return pools
+
+    def get_ceph_df(self, sentry_unit):
+        """Return dict of ceph df json output, including ceph pool state.
+
+        :param sentry_unit: Pointer to amulet sentry instance (juju unit)
+        :returns: Dict of ceph df output
+        """
+        cmd = 'sudo ceph df --format=json'
+        output, code = sentry_unit.run(cmd)
+        if code != 0:
+            msg = ('{} `{}` returned {} '
+                   '{}'.format(sentry_unit.info['unit_name'],
+                               cmd, code, output))
+            amulet.raise_status(amulet.FAIL, msg=msg)
+        return json.loads(output)
+
+    def get_ceph_pool_sample(self, sentry_unit, pool_id=0):
+        """Take a sample of attributes of a ceph pool, returning ceph
+        pool name, object count and disk space used for the specified
+        pool ID number.
+
+        :param sentry_unit: Pointer to amulet sentry instance (juju unit)
+        :param pool_id: Ceph pool ID
+        :returns: List of pool name, object count, kb disk space used
+        """
+        df = self.get_ceph_df(sentry_unit)
+        pool_name = df['pools'][pool_id]['name']
+        obj_count = df['pools'][pool_id]['stats']['objects']
+        kb_used = df['pools'][pool_id]['stats']['kb_used']
+        self.log.debug('Ceph {} pool (ID {}): {} objects, '
+                       '{} kb used'.format(pool_name, pool_id,
+                                           obj_count, kb_used))
+        return pool_name, obj_count, kb_used
+
+    def validate_ceph_pool_samples(self, samples, sample_type="resource pool"):
+        """Validate ceph pool samples taken over time, such as pool
+        object counts or pool kb used, before adding, after adding, and
+        after deleting items which affect those pool attributes.  The
+        2nd element is expected to be greater than the 1st; 3rd is expected
+        to be less than the 2nd.
+
+        :param samples: List containing 3 data samples
+        :param sample_type: String for logging and usage context
+        :returns: None if successful, Failure message otherwise
+        """
+        original, created, deleted = range(3)
+        if samples[created] <= samples[original] or \
+                samples[deleted] >= samples[created]:
+            return ('Ceph {} samples ({}) '
+                    'unexpected.'.format(sample_type, samples))
+        else:
+            self.log.debug('Ceph {} samples (OK): '
+                           '{}'.format(sample_type, samples))
+            return None